Over centre latches, or over center latches, are mechanical fasteners that join surfaces. They normally connect two separated flat surfaces and are known as toggle, strike, or catch latches. Once the loop of the latch is attached to the catch, it takes significant force to disconnect them. When locked, over centre latches ensure that surfaces, panels, or objects are securely fastened and unable to be disconnected or opened.
Though over centre latches come in a wide variety of designs and configurations, all of the different types have the basic structure of a base plate with a lever or latch, attached loop, and a catch plate. Tension is created once the loop is connected to the catch plate.
The concept of an over centre latch is built on the principles of levers and pivots. The toggle action over the centre lock point reaches a centered position to be securely locked. Unlocking the mechanism is simply a matter of lifting the latch to release the loop from the catch.
There are certain considerations to be evaluated when purchasing an over centre latch. The first, and most important, is the maximum load to which it will be subjected. Each type of latch has a load capacity. For the most success, it is suggested to use a latch that works safely at half its tensile strength with a catch plate that has the same strength as the latch.
The four categories of over centre latches are light, medium, heavy, and super heavy duty. They are classified according to their tensile strength, which can vary from 24 lbs. for light tensile strength to several tons for super heavy duty. Medium and heavy-duty latches have load maximum capacities of 1500 lbs. and a little over a ton, respectively.
Over centre latches are normally made from mild steel, or T304 and T306 stainless steel. They do come in other metals but steel, for its strength, is the most common metal used. Various finishes can be added for extra protection, which include zinc and electrophoretic paint.
Extra features include safety catches, sealing pins, holes in the latch to fit a padlock, and key locking mechanisms. These additions increase the security of the latch and offer extra protection. Aside from preventing theft, they keep the latch from disconnecting when there is excessive movement or vibrations.
Over centre latches are stable, strong, reliable, and dependable with the convenience of quick release for instant access. Their wide selection ensures that there is one that can exactly fit any application, conditions, or requirements.